package company.divide;

import java.util.Scanner;

/**
 * 37 解数独
 * 编写一个程序，通过填充空格来解决数独问题。
 * <p>
 * 数独的解法需 遵循如下规则：
 * <p>
 * 数字 1-9 在每一行只能出现一次。
 * 数字 1-9 在每一列只能出现一次。
 * 数字 1-9 在每一个以粗实线分隔的 3x3 宫内只能出现一次。（请参考示例图）
 * 数独部分空格内已填入了数字，空白格用 '.' 表示。
 * <p>
 *  
 * <p>
 * 示例 1：
 * <p>
 * <p>
 * 输入：board = [["5","3",".",".","7",".",".",".","."],["6",".",".","1","9","5",".",".","."],[".","9","8",".",".",".",".","6","."],["8",".",".",".","6",".",".",".","3"],["4",".",".","8",".","3",".",".","1"],["7",".",".",".","2",".",".",".","6"],[".","6",".",".",".",".","2","8","."],[".",".",".","4","1","9",".",".","5"],[".",".",".",".","8",".",".","7","9"]]
 * 输出：[["5","3","4","6","7","8","9","1","2"],["6","7","2","1","9","5","3","4","8"],["1","9","8","3","4","2","5","6","7"],["8","5","9","7","6","1","4","2","3"],["4","2","6","8","5","3","7","9","1"],["7","1","3","9","2","4","8","5","6"],["9","6","1","5","3","7","2","8","4"],["2","8","7","4","1","9","6","3","5"],["3","4","5","2","8","6","1","7","9"]]
 * 解释：输入的数独如上图所示，唯一有效的解决方案如下所示：
 * <p>
 * <p>
 *  
 * <p>
 * 提示：
 * <p>
 * board.length == 9
 * board[i].length == 9
 * board[i][j] 是一位数字或者 '.'
 * 题目数据 保证 输入数独仅有一个解
 * <p>
 * 来源：力扣（LeetCode）
 * 链接：https://leetcode.cn/problems/sudoku-solver
 * 著作权归领扣网络所有。商业转载请联系官方授权，非商业转载请注明出处。
 */
public class SolveSudoku37 {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        String replace = sc.nextLine().replace("[[", "").replace("]]", "");
        String[] split = replace.split("],\\[");
        char[][] board = new char[9][9];
        for (int i = 0; i < split.length; i++) {
            String[] s = split[i].replace(" ", "").split(",");
            for (int j = 0; j < s.length; j++) {
                board[i][j] = s[j].charAt(1);
            }
        }
        solveSudoku(board);
        System.out.println(board);
    }

    public static void solveSudoku(char[][] board) {
        if (board == null || board.length == 0) {
            return;
        }
        solve(board);
        for (int i =0 ; i<9; i++) {
            System.out.println(board[i]);
        }
    }

    public static boolean solve(char[][] board) {
        for (int i = 0; i < 9; i++) {
            for (int j = 0; j < 9; j++) {
                if (board[i][j] == '.') {
                    for (char c = '1'; c <= '9'; c++) {
                        if (isValid(board, i, j, c)) {
                            board[i][j] = c;
                            if (solve(board)) {
                                return true;    //如果棋盘能解决的话，就说明问题解决了，return true
                            } else {
                                board[i][j] = '.';  //恢复上一个状态，回溯
                            }
                        }
                    }
                    return false;
                }
            }
        }
        return true;
    }

    public static boolean isValid(char[][] board, int row, int col, char c) {
        for (int i = 0; i < 9; i++) {
            if (board[row][i] != '.' && board[row][i] == c) {
                return false;
            }
            if (board[i][col] != '.' && board[i][col] == c) {
                return false;
            }

           // 为什么九宫格是这样判断
            if (board[3 * (row / 3) + i / 3][3 * (col / 3) + i % 3] != '.' &&
                    board[3 * (row / 3) + i / 3][3 * (col / 3) + i % 3] == c) {
                return false; //检查3*3的格子是否合法
            }
        }

        return true;
    }

}
